This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A122259 #11 Feb 16 2025 08:33:02 %S A122259 11,23,29,31,41,43,47,53,59,61,67,71,79,83,89,101,103,107,113,127,131, %T A122259 137,139,149,151,157,167,173,179,181,191,197,199,211,223,227,229,233, %U A122259 239,241,251,263,269,271,277,281,283,293,307,311,313,317,331,337,347 %N A122259 Primes p such that p - 1 is not 3-smooth. %H A122259 Charles R Greathouse IV, <a href="/A122259/b122259.txt">Table of n, a(n) for n = 1..10000</a> %H A122259 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PierpontPrime.html">Pierpont Prime</a> %F A122259 A122257(a(n)) = 0; %F A122259 A006530(a(n) - 1) > 3. %F A122259 a(n) ~ n log n. - _Charles R Greathouse IV_, Oct 29 2018 %t A122259 smooth3Q[n_] := n == 2^IntegerExponent[n, 2]*3^IntegerExponent[n, 3]; %t A122259 Select[Prime[Range[100]], !smooth3Q[#-1]&] (* _Jean-François Alcover_, Oct 17 2021 *) %o A122259 (PARI) is(n)=my(q=n-1); q>>=valuation(q,2); q/=3^valuation(q,3); q>1 && isprime(n) \\ _Charles R Greathouse IV_, Oct 29 2018 %Y A122259 Cf. A005109, A006530, A122257. %K A122259 nonn,easy %O A122259 1,1 %A A122259 _Reinhard Zumkeller_, Aug 29 2006